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61.
Variability in herbivore-induced odour emissions among maize cultivars and their wild ancestors (teosinte) 总被引:10,自引:0,他引:10
Summary. Maize plants respond to caterpillar feeding with the release of relatively large amounts of specific volatiles, which are known to serve as cues for parasitoids to locate their host. Little is known about the genetic variability in such herbivore-induced plant signals and about how the emissions in cultivated plants compare to those of their wild relatives. For this reason we compared the total quantity and the qualitative composition of the odour blend among eleven maize cultivars and five wild Zea (Poaceae) species (teosinte), as well as among the offspring of eight Zea mays mexicana plants from a single population. Young plants were induced to release volatiles by mechanically damaging the leaves and applying oral secretions of Spodoptera littoralis (Lepidoptera: Noctuidae) caterpillars to the wounded sites. Volatiles were collected 7 h after treatment and subsequently analysed by gas chromatography. The total amounts of volatiles released were significantly different among maize cultivars as well as among the teosintes. Moreover, striking differences were found in the composition of the induced odour blends. Caryophyllene, for instance, was released by some, but not all varieties and teosintes, and the ratios among monoterpenes and sesquiterpenes varied considerably. The offspring of different mother plants of the Z. m. mexicana population showed some variation in the total amounts that they released, but the composition of the odour blend was very consistent within the population of this teosinte species. We discuss the ecological significance of these findings in terms of specificity and reliability of induced plant signals for parasitoids. 相似文献
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63.
Edwin Corporan Richard Reich Orvin Monroig Matthew J. DeWitt Venus Larson Ted Aulich 《Journal of the Air & Waste Management Association (1995)》2013,63(7):940-949
Abstract The impacts of biodiesel on gaseous and particulate matter (PM) emissions of a JP-8–fueled T63 engine were investigated. Jet fuel was blended with the soybean oil-derived methyl ester biofuel at various concentrations and combusted in the turbine engine. The engine was operated at three power settings, namely ground idle, cruise, and takeoff power, to study the impact of the biodiesel at significantly different pressure and temperature conditions. Particulate emissions were characterized by measuring the particle number density (PND; particulate concentration), the particle size distribution, and the total particulate mass. PM samples were collected for off-line analysis to obtain information about the effect of the biodiesel on the polycyclic aromatic hydrocarbon (PAH) content. In addition, temperature-programmed oxidation was performed on the collected soot samples to obtain information about the carbonaceous content (elemental or organic). Major and minor gaseous emissions were quantified using a total hydrocarbon analyzer, an oxygen analyzer, and a Fourier Transform IR analyzer. Test results showed the potential of biodiesel to reduce soot emissions in the jet-fueled turbine engine without negatively impacting the engine performance. These reductions, however, were observed only at the higher power settings with relatively high concentrations of biodiesel. Specifically, reductions of ~15% in the PND were observed at cruise and takeoff conditions with 20% biodiesel in the jet fuel. At the idle condition, slight increases in PND were observed; however, evidence shows this increase to be the result of condensed uncombusted biodiesel. Most of the gaseous emissions were unaffected under all of the conditions. The biodiesel was observed to have minimal effect on the formation of polycyclic aromatic hydrocarbons during this study. In addition to the combustion results, discussion of the physical and chemical characteristics of the blended fuels obtained using standard American Society for Testing and Materials (ASTM) fuel specifications methods are presented. 相似文献
64.
Sue Kimbrough Ted Palma Richard W. Baldauf 《Journal of the Air & Waste Management Association (1995)》2014,64(3):349-359
Exposures to mobile source air toxics (MSATs) have been associated with numerous adverse health effects. While thousands of air toxic compounds are emitted from mobile sources, members of a subset of compounds are considered high priority due to their significant contribution to cancer and noncancer health risks and the contribution of mobile sources to total exposure as evaluated by the U.S. Environmental Protection Agency (EPA) National-Scale Air Toxics Assessments (NATA). These pollutants include benzene, 1,3-butadiene, ethylbenzene, acrolein, acetaldehyde, formaldehyde, naphthalene, polycyclic organic matter, and diesel particulate matter/organic gases. This study provided year-long trends of benzene, 1,3-butadiene, acrolein, acetaldehyde, and formaldehyde in Las Vegas, NV. Results indicated that MSAT concentrations often did not exhibit trends typical of other primary emitted pollutants in this study. Instead, other mobile sources beyond the highway of interest contributed to the measured values, including a major arterial road, a large commercial airport, and a nearby parking lot. The data were compared with relevant census-tract NATA estimates, with estimated ambient 1,3-butadiene concentrations similar to the measured values. Measured benzene values were much lower relative to the NATA total ambient benzene concentrations. Measured acrolein values were much higher relative to the NATA total acrolein concentrations. Measured acetaldehyde and formaldehyde values were also higher relative to the NATA total acetaldehyde and formaldehyde concentrations for all wind conditions and downwind conditions. Some possible explanations for these differences include nearby sources influencing the measured values; meteorological influences that may not be well captured by the NATA modeling regime; chemical reactivity of measured compounds; and additional explanatory variables may be needed for certain urban areas in order to accurately disaggregate anthropogenic air toxics emissions.
Implications: Comparison of air toxics concentrations measured at four long-term near-road sites in Las Vegas, NV, show generally good agreement with the EPA 2005 NATA total ambient concentrations. Measured concentrations did not compare as well with EPA 2005 NATA for the on-road mobile portion of the ambient concentrations. This highlights the complexity of air toxic emission sources and impacts in urban areas, especially around large highway facilities; NATA's inability to capture local-scale meteorology and fine-scale ambient gradients; and that additional explanatory variables may be needed for certain urban areas in order to accurately disaggregate anthropogenic air toxics emissions. 相似文献
65.
Role of Propagule Size in the Success of Incipient Colonies of the Invasive Argentine Ant 总被引:4,自引:0,他引:4
Abstract: Factors that contribute to the successful establishment of invasive species are often poorly understood. Propagule size is considered a key determinant of establishment success, but experimental tests of its importance are rare. We used experimental colonies of the invasive Argentine ant ( Linepithema humile ) that differed both in worker and queen number to test how these attributes influence the survivorship and growth of incipient colonies. All propagules without workers experienced queen mortality, in contrast to only 6% of propagules with workers. In small propagules (10–1,000 workers), brood production increased with worker number but not queen number. In contrast, per capita measures of colony growth decreased with worker number over these colony sizes. In larger propagules ( 1,000–11,000 workers), brood production also increased with increasing worker number, but per capita brood production appeared independent of colony size. Our results suggest that queens need workers to establish successfully but that propagules with as few as 10 workers can grow quickly. Given the requirements for propagule success in Argentine ants, it is not surprising how easily they spread via human commerce. 相似文献
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67.
Franke Alastair Falk Knud Hawkshaw Kevin Ambrose Skip Anderson David L. Bente Peter J. Booms Travis Burnham Kurt K. Ekenstedt Johan Fufachev Ivan Ganusevich Sergey Johansen Kenneth Johnson Jeff A. Kharitonov Sergey Koskimies Pertti Kulikova Olga Lindberg Peter Lindström Berth-Ove Mattox William G. McIntyre Carol L. Mechnikova Svetlana Mossop Dave Møller Søren Nielsen Ólafur K. Ollila Tuomo Østlyngen Arve Pokrovsky Ivan Poole Kim Restani Marco Robinson Bryce W. Rosenfield Robert Sokolov Aleksandr Sokolov Vasiliy Swem Ted Vorkamp Katrin 《Ambio》2020,49(3):762-783
Ambio - The peregrine falcon (Falco peregrinus) and the gyrfalcon (Falco rusticolus) are top avian predators of Arctic ecosystems. Although existing monitoring efforts are well established for both... 相似文献
68.
69.
Index of Alien Impact: A Method for Evaluating Potential Ecological Impact of Alien Plant Species 总被引:1,自引:0,他引:1
Teresa K. Magee Paul L. Ringold Michael A. Bollman Ted L. Ernst 《Environmental management》2010,45(4):759-778
Alien plant species are stressors to ecosystems and indicators of reduced ecosystem integrity. The magnitude of the stress
reflects not only the quantity of aliens present, but also the quality of their interactions with native ecosystems. We develop
an Index of Alien Impact (IAI) to estimate the collective ecological impact of in situ alien species. IAI summarizes the frequency of occurrence and potential
ecological impact (Invasiveness-Impact Score (I
i
)) of individual alien species for all aliens present in a particular location or community type. A component metric, I
i
, is based on ecological species traits (life history, ecological amplitude, and ability to alter ecosystem processes) that
reflect mechanisms, which can increase impact to ecosystem structure and function. While I
i
is less complex than some other multi-metric rankings of alien impact, it compares well to these metrics and to qualitative
judgments. IAI can be adapted for different ecological settings by modifying the set of species traits incorporated in I
i
to reflect properties likely to breach biotic and abiotic barriers or alter ecosystem function in a particular region or
community type of interest. To demonstrate our approach, we created versions of IAI and I
i
, applicable to the diverse streamside vegetation of a river basin (19,631 km2) spanning low-elevation arid to mesic montane habitats in eastern Oregon, USA. In this demonstration effort, we (1) evaluate
relationships of IAI to metrics describing invasion level, and (2) illustrate the potential utility of IAI for prioritizing
alien species management activities and informing restoration goals. 相似文献
70.